Energy storage apparatus and article of manufacture

ABSTRACT

An energy storage apparatus and article of manufacture is disclosed. In one embodiment, the energy storage apparatus comprises a jelly roll, having a first and second sheet and a first and second separator member, and at least one terminal element. In another embodiment, an article of manufacture comprising forming a cylindrical housing and stamping a longitudinal indentation on an exterior surface of the cylindrical housing is disclosed. In one alternate embodiment, the longitudinal indentation is adapted to slowly fracture under pressure exerted on an interior surface of the cylindrical housing, thereby preventing catastrophic failure, such as for example an explosion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of and is a continuation ofU.S. patent application Ser. No. 11/558,424, which was filed on Nov. 9,2006, and which is incorporated by reference herein for all purposes,and also claims the benefit of U.S. provisional patent application60/734,806, filed on Nov. 9, 2005, which is incorporated by referenceherein for all purposes.

FIELD OF INVENTION

The subject matter of this application relates generally to capacitorsand capacitor housings and relates more particularly to double-layercapacitors and double-layer capacitor housings.

BACKGROUND

Conventional capacitor technology is well known to those skilled in theart. The energy and power density that can be provided by conventionalcapacitor technology is typically low, for example, conventionalcapacitors are normally capable of providing less than 0.1 Wh/kg.Applications that require greater energy density from an energy source,therefore, typically do not rely on conventional capacitor technology.The amount of energy delivered by conventional capacitor technology canbe increased, but only by increasing the number of capacitors.

Relatively recently in the energy storage field, a capacitor technologycalled double-layer capacitor technology, also referred to asultra-capacitor technology and super-capacitor technology, has beendeveloped. Double layer capacitors store electrostatic energy in apolarized electrode/electrolyte interface layer that is created by anelectrical potential formed between two electrode films when a finishedcapacitor cell is immersed in an electrolyte. When the electrode formsand associated collecting plates are immersed in the electrolyte, afirst layer of electrolyte dipole and a second layer of chargedparticles and a second layer of charging species is formed (hence thename “double-layer” capacitor). Individual double-layer capacitor cellsare typically available with values greater than 0.1 Farad and above.For any given housing size, a double-layer capacitor cell may provide onthe order of about 100-1000 times, or more, as much capacitance as aconventional capacitor cell. In one example, the energy density providedby a double-layer capacitor is on the order of about 10 Wh/kg, and thepower density is on the order of about 10,000 W/kg.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of an embodiment of a double-layercapacitor structure.

FIG. 2 shows a top view of a jelly-roll double layer capacitor structurebeing wound.

FIG. 3 shows an embodiment of a battery form factor sized capacitorstructure.

FIG. 4 shows a perspective view of an embodiment of a jelly-roll typedouble-layer capacitor cell.

FIG. 5A shows a cross-section of an embodiment of a double-layercapacitor structure.

FIG. 5B shows an embodiment of a cover for a double-layer capacitorstructure.

FIG. 5C shows a stack of a plurality of covers shown in FIG. 5B fordouble-layer capacitors.

FIG. 5D shows an embodiment of a conductor used in a construction of adouble-layer capacitor.

FIG. 5E shows an embodiment of a housing for a double-layer capacitor.

FIG. 5F shows an embodiment of a jelly-roll positioned within a housing.

FIG. 5G shows another embodiment of a housing for a double-layercapacitor.

FIG. 5H shows an embodiment of an electrode layer of a double-layercapacitor.

FIG. 5I shows an embodiment of a seal between a housing and a cover of adouble-layer capacitor.

FIG. 5J shows a cross-section of an embodiment of a double-layercapacitor.

FIG. 5K shows a cross-section of an embodiment of a double-layercapacitor.

FIG. 5L shows a perspective view of an embodiment of a double-layercapacitor housing.

FIG. 5M shows a perspective view of an embodiment of a double-layercapacitor housing.

FIG. 5N shows a plan view of an embodiment of a plurality ofinterconnectable double-layer capacitor structures.

DETAILED DESCRIPTION

In one embodiment, four 2600 F|2.5 V|60 mm×172 mm|525 g| sealedcapacitors are interconnected as a series string of capacitors. In oneembodiment, it has been identified that when charged to 10 volts, over1500 amps of instantaneous peak current may flow through such fourseries connected capacitors at through their terminals. Accordingly, inone embodiment each capacitor preferably comprises terminals andinterconnections that are sized to safely carry 1500 amps of peakcurrent. Although only four series connected capacitors are discussed,the scope of the embodiments and inventions described herein envisionsthe interconnection of less or more than four series and/or parallelconnected capacitors.

Referring now to FIG. 1 there are seen structures of a double-layercapacitor. In FIG. 1, double-layer capacitor sheet 10 like structuresare shown in a cross-section. The sheets 10 can be visualized to extendinward and outward from FIG. 1. Each sheet 10 comprises two electrodefilms 40 and a current collector plate 60. First surface of theelectrode films 40 are coupled to the collector plate 60. In oneembodiment, the electrode films 40 are bonded to a collector plate 60 bya respective conductive adhesive layer 50. In one embodiment, theelectrode films 40 are formed from a fibrillized blend of dry Teflon anddry activated and dry conductive carbon particles without use of anysolvent, liquid, and the like (i.e. dry particle based) process steps.In one embodiment, the adhesive layers 50 are formed from a blend of dryconductive carbon particles and dry binder particles without use of anysolvent liquid, and the liked (i.e., dry particle based) process steps.In other embodiments, the electrode films 40 and adhesive layers may beformed by other processes known to those skilled in the art, includingby extrusion and/or coating. First and second sheets 10 are separated bya first separator 30. A second separator 30 is provided to comprise anoutermost separator (relative to the center of jelly-roll that issubsequently formed), as is illustrated by FIG. 2. The two sheets 10 arerolled together in an offset manner that allows an exposed end of acollector plate 60 of the first sheet 10 to extend in one direction andan exposed end of a collector plate 60 of the second sheet 10 is extendin a second direction. The resulting capacitor geometry is known tothose skilled in the art as a jelly-roll and is illustrated in a topview by FIG. 2. In one embodiment, the current collector plate 60comprises an etched or roughened aluminum foil of about 30 microns inthickness. In one embodiment, the adhesive layers 50 comprise athickness of about 5 to 15 microns. In one embodiment, the electrodefilms 40 comprise a thickness of about 80 to 250 microns. In oneembodiment, the paper separator 70 comprise a thickness of about 20-40microns.

Double-layer capacitors have intrinsic properties that limit theirmaximum charging voltage to a theoretical value of no more than about4.0 volts. In one embodiment, a nominal maximum charging voltage of adouble-layer capacitor is in a range of about 2.5 or 3.0 volts, which itis identified is a voltage that encompasses the output voltage of a widerange of available rechargeable and non-rechargeable batteries.

It is identified that double-layer capacitors can be designed tocomprise a power density that is greater than lead acid, and many NickelCadmium, Lithium, and Alkaline type batteries; and with an energydensity that approaches that of, or overlaps, the energy densityavailable from lead acid, Nickel Cadmium, Lithium, and Alkalinebatteries.

Referring now to FIG. 3, three is seen a battery form factor sizedcapacitor. In one embodiment, a double-layer capacitor is designed toconform to a battery form factor. Although an exemplary embodimentherein describes a battery form factor sized capacitor, the presentinvention will be understood to fine applicability with other formfactors, whether standardized or not. Those skilled in the art willunderstand that standardized battery form factor sized housing may varywithin tolerances that have been established and accepted bymanufacturers and those skilled in the art. The dimensions ofstandardized battery form factor sized housing can be obtained fromintentional standards body IEC located at Central Office, 3, rue deVarembé, P.O. Box 131, CH-1211 GENEVA 20, Switzerland. Primary cell fromfactor standards known to those skilled in the art that are within thescope of the present invention are referenced in International StandardIEC Standard 60086-1—Ed. 9.0, which documents primary batteries withrespect to their electrochemical system, dimensions, nomenclature,terminal configurations, markings, test methods, typical performancesafety and environmental aspects, and which is incorporated herein byreferences. Secondary cell form factor standards known to those skilledin the art that are within the scope of the present invention arereferenced in International Standard IEC Standard 61951-1—Ed. 2.0, whichdocuments secondary batteries with respect to their electrochemicalsystems, dimensions, nomenclature, terminal configurations, markings,test methods, typical performance safety and environmental aspects, andwhich is incorporated herein by reference. Standardized battery formfactor housings and terminal dimensions and configurations can also beobtained from American National Standards Institute (ANSI) located atWashington D.C. Headquarters 1819 L Street, NW (between 18^(th) and19^(th) Streets), 6^(th) floor Washington, D.C. 20036. ANSI standardsfor batteries are known by those skilled in the art as ANSI/NEDAstandards. For example, an ANSI standard for D-cell sized batteryhousings is known as ANSI/NEDA 13A, an ANSI standard for C-cell sizebattery housings is known as ANSI/NEDA 14A, an ANSI standard for AA-cellsized battery housings is known as ANSI/NEDA 15A, an ANSI standard forD-cell sized battery housings is known as ANSI/NEDA 24A, and an ANSIstandard for 9 volt sized battery housings is known as ANSI/NEDA 1604A.

In one embodiment, a battery form factor sized housing manufacture as anEnergizer™ brand D-cell sized batter comprises a diameter of about32.3-34.2 mm and height of 59.5-61.5 mm. Accordingly, in one embodiment,a battery form factor sized capacitor housing 100 comprises a diameterof about 33+0/−1 mm and a height of about 61.5+0/−2 mm, which aredimensions that are within the ANSI/NEDA and IEC dimensions for D-cellsized battery housings, and Energizer brand batter D-cell dimensions. Itis understood that, D-cell dimensions are illustrative of one possiblestandardized battery form factor sized housing that is within the scopeof the present invention, which should be limited only by the scope ofthe claims. For example, a C-cell form factor sized capacitor housingcan comprises a diameter of about 25.2+0/−1 mm and a height of about49.0+0/−2 mm, an AA-cell form factor sized capacitor housing cancomprise a diameter of about 13.0+0/−1 mm and a height of about50.0+0/−2 mm, and a AAA-cell form factor sized capacitor housing cancomprise a diameter of about 10.0+0/−1 mm and a height of 44.0+0/−2 mm.In one embodiment, a double-layer capacitor in a D-cell form factorsized capacitor housing 100 has been demonstrated to provide 425 F, 3.2mOhm at about 2.5 Vdc in a 56 g cell and an energy density of about 6.5Wh/kg and a power density of about 8.7 kW/kg.

In one embodiment, a capacitor housing 100 may be provided with externalelectrode connections/connectors/terminals 70, 80 similar to, or thesame as, those of standardized batteries. Inclusion of battery styleterminal ends on a capacitor housing 100 enables that the housing can beprovided to easily connect to apparatus that utilize battery styleconnectors of a reverse sex. Because existing standardized battery styleconnectors, and modules that use them, can be readily obtained frommanufacturers, redesign time and costs can be appreciably reduced whenimplementing one or more of the embodiments described here.

Standardized battery style connections/connectors/terminals 70, 80 canalso be used to connect multiple capacitor housings 100 together. Forexample, as with batteries, the operating voltage of a double-layercapacitor 150 may be increased by connecting two or more double-layercapacitors in series. The use of standardized battery styleconnections/connectors/terminals 70, 80 facilitates such seriesconnections. As well, standardized battery styleconnections/connectors/terminals 70, 80 can be used to facilitateparallel connections. Battery style connections 70, 80 allow easy dripin capacitor replacement of batteries to be made. The benefits andadvantages of the embodiments described herein enable easy connectionand replacement of battery technology with double-layer capacitortechnology, and thus, increase the number of potential applications thatdouble-layer capacitors can be used in. Furthermore, a change of energycomponent type, from batter to double-layer capacitor, finds interest inapplications where maintenance cost is a key factor, or wherecyclability is important.

In one embodiment, it is identified that the ends 70, 80 of a batteryform factor sized capacitor housing 100 lend themselves well to ageometrical design that exhibits a relatively large electricalconductive surface area, as compared to conventional capacitor housingsthat provide small diameter leads, terminals, etc. For example, in oneembodiment, a D-cell battery form factor sized capacitor housing 100 maybe designed to comprise conductive end surface area(s) of greater than90 mm². The large electrical contact surface area at the ends of aD-cell form factor sized capacitor housing 100 allows that high currentmay flow through the end with minimal electrical loss. Becausedouble-layer capacitors can supply or receive higher current thancomparable batteries, the large surface area ends 70, 80 can be usedadvantageously for this purpose. Large surface area ends 70, 80 alsoallow that the ends may be provided in many geometrical variations andyet remain within the required dimensions of a particular battery formfactor. For example, appropriate dimensioning of the ends 70, 80 may bemade to provide large screw-in type connections, mechanical pressuretype connections, welding/solder type connections, as well as othersthat in the capacitor prior art would not be practical or not possible.

Double-layer technology is now capable of being provided with energyand/or power density performance characteristics that approach or exceedthose of batteries. Accordingly, it has been identified thatdouble-layer capacitor technology can housed in a standardized batteryform factor sized housing to supplement, or substitute for, equivalentsized batteries. Double-layer capacitor technology in a battery formfactor sized housing 100 may also improve upon battery technology. Forexample, a D-cell sized double-layer capacitor 150 can provide many morecharge/recharge cycles than may achieved by a D-cell sized rechargeablebattery. Because double-layer capacitors utilize an electrostaticstorage mechanism, they can be cycled through hundreds of thousands ofcharges and discharges without performance degradation, which compareswith life cycles of less than 1000 for rechargeable batteries.

Although discussed with reference to a D-cell form factor sized housing100, the present invention is not limited to a D-cell form factorhousing and/or standardized battery electrodeconnections/connectors/terminals 70, 80. For example, one or more of theabove identified principles and advantages can be used to effectuateother battery form factor sized capacitor housings and connectors. Forexample, it is identified that many power tools are now powered bybatteries in a power tool specific form factor housing. In oneembodiment, double-layer capacitor(s) may be housed is such amanufacturer specific housing. Although some double-layer capacitors maynot have the energy density of batteries, the do typically have morepower density than batteries, and thus, can be used as a short-termsubstitute for a power tool battery pack. Because a double-layercapacitor based energy source in a battery form factor sized capacitorhousing can be recharged more quickly than a battery, for example, onthe order of 15 seconds or so, as opposed to the tens of minutes for abattery, double-layer capacitor technology can be utilized as a batterysubstitute or supplement when re/charge times are critical.

Referring now to FIG. 4, there is seen a perspective view of ajelly-roll type double-layer capacitor cell. In one embodiment, ends ofone offset collector extend from one end 1212 of a rolled double-layercapacitor 1200, and ends of another offset collector extend (representedby exemplary collector extensions 1202) from another end 1206. In oneembodiment, the capacitor is rolled about a centrally disposed rod,which after rolling may be removed to thus leave a centrally disposedvoid within the jelly-roll.

Referring to FIG. 5 a, and preceding Figures as needed, in oneembodiment a D-cell form factor double-layer capacitor comprises ahousing 100, a cover 200, and a jelly-roll electrode 300. In oneembodiment, the housing comprises aluminum, and the cover 200 comprisesaluminum.

With reference to FIG. 5 b, and preceding Figures as needed, in oneembodiment the cover 200 may be extruded, shaped, machined, molded,and/or stamped to conform or comprise the general shape of one end of aD-cell battery. As seen in FIG. 5 b, in its unassembled form, the cover200 comprises a circular geometry with an upper 201 and lower 202surface and curved outer periphery 203. The lower surface 202 at theouter periphery is later coupled to the housing 100 during a processthat forms a seal between the cover 200 and the housing 100.

An assembled double-layer capacitor comprises a positive and negativepolarity. To electrically separate such polarity, an electricalinsulator or insulation may be provided, for example, as between a cover200 and a housing 100. In one embodiment, a sealant may also be providedbetween the cover 200 and the housing 100.

In one embodiment, it is identified that electrical connection needs tobe made between the cover 200 and the jellyroll 300, and for thisreason, a portion of the surface 202 to which insulator has been appliedis preferably left bare of insulator. In one embodiment, a centralportion 205 of the surface 202 is left bare.

It is identified that when a material is required to be applied to onlya portion of a cover 200, the bare portion of the cover is typicallymasked from the material. Such masking, as well as application ofmaterial, is time consuming in that it requires individual handling ofeach cover as well as other processes.

Referring to FIG. 5 d, and preceding Figures as needed, in a subsequentstep, a semi rigid electrically conductive metal 600 is connected to abare central portion 205 of the bottom surface 202 of a cover 200.Initially the metal 600 is formed of a 0.6 mm thick flat sheet ofaluminum. The metal 600 is of sufficient cross-sectional area to be ableto pass 1500 amps of current without damage to the metal 600 or theconnections made to couple the metal to the cover and jelly-roll. Themetal is formed into a geometry that comprises a first end 600 a, asecond end 600 b, and a middle portion 600 c. In one embodiment, at thesecond 600 b, the metal comprises a portion that extends generallyperpendicular to an axis formed through the first portion 600 and themiddle portion 600 c. In one embodiment, the second end 600 b, comprisesa centrally disposed void 600 d. The void may comprise a slot, a hole,or other opening. Before attachment to a cover 200, the metal 600 may bebent at the middle portion 600 c twice such that when viewed in across-section the metal comprises a shape similar to that of an “M”. Inthis “M” configuration, the first end 600 a is attached to a centralportion 205 of a cover 200. Attachment is preferably made be welding,for example, by a spot weld or a laser weld. After attachment of a metal600 to a cover 200, the cover is placed aside until needed, as will bedescribed further below.

Referring to FIG. 5 e, and preceding Figures as needed, in a subsequentstep, a housing 100 is obtained. In one embodiment the housing 100 isformed to comprise at its open end an inwardly curved neck portion 100 aand an outwardly directed lip portion 100 b. This geometry effectuatessealing between a cover 200 and the housing 100 during a subsequentcurling/sealing step. Other geometries are also within the scope of theinvention. In one embodiment, forming (for example, necking, sealing)etc. may be effectuated after insertion of a jellyroll 300 within thehousing, with implementation of such processes known to those skilled inthe art. In one embodiment, the housing 100 may be subject toapplication of a stamping or other forming force during manufacture ofthe housing, which forms a longitudinal indentation 100 c into thehousing. It is identified that the indentation 100 c may be used toweaken the housing to an extent that allows the indentation to slowlycrack or open under a specific pressure. The ability to slowly crack oropen protects a sealed capacitor product from exploding catastrophicallyduring some of its failure modes. In other words, the indentation 100 ccan provide functionality similar to that of a “fuse,” wherein at acertain pressure, the indentation safely renders the capacitor to be nonfunctional.

The exterior and interior of the housing 100 are cleaned usingtechniques known to those skilled in the art.

In one embodiment, an electrical insulator 100 e is applied to theexterior and the interior of the housing 100. In one embodiment, theinsulator 100 e is applied to the housing while the can is subject tospinning about a central longitudinal axis. In one embodiment, theinsulator 100 e is applied by spraying the insulator. In one embodiment,the insulator 100 e is applied to only a portion of the exterior and theinterior of the housing 100. For example, it is identified that theinterior and exterior of the housing 100 may need be coated to an extentneeded to effectuate subsequent sealing of the housing 100 by a cover200.

Referring to FIG. 5 f, and preceding Figures as needed, in oneembodiment, a jelly-roll 300 comprising offset collectors is positionedwithin an open end of a housing 100. It is identified in an embodimentwherein the housing 100 is provided with one polarity and the cover isprovided with the opposite polarity, an orientation of the jelly-roll300 within the housing 100 can affect performance of a final capacitorproduct. For example, when an extending collector associated with theoutermost electrode layer 300 a is coupled to the positive polarity ofthe cover 200 (i.e. “flipped” jelly-roll orientation), the positivepolarity of the cover can become electrically shorted by the outermostelectrode layer to the negative polarity of the housing. Although, inone embodiment jelly-roll 300 may be physically separated from thehousing 100 by an outermost paper separator 30 (FIG. 1 d), because paperseparator 30 is porous, it does not act to fully electrically separatethe jelly-roll from the housing when subsequently impregnated withconductive electrolyte. As well, use of paper separator 30 may act tothermally isolate the jelly-roll 300 from the housing 100, which may actto limit thermal dissipation of heat generated by the jelly-roll 300 bythe housing, which may as a consequence reduce the lifetime of thejelly-roll.

Referring to FIG. 5 g, and preceding Figures as needed, in a “flipped”jelly-roll orientation, to provide electrical insulation from a housing100, an additional outermost sleeve of thin plastic or other insulativematerial 300 b may be applied to a jelly-roll 300.

Referring again to FIG. 5 e, in one embodiment, an electrical insulatoris applied from a top portion of the walls of interior of the housing100 to a bottom portion. In one embodiment, the electrical insulator isapplied as a fixed spray during a time the housing is rotated. Suchcoating can be applied as a natural extension of coating the upper outerand upper inner portions of the housing 100. As a result, in anembodiment wherein a jelly-roll is inserted in a flipped orientation, aswell as in a flipped orientation, when an insulator 100 e is applied tothe interior walls of the housing, an insulating material 300 b may notneed to be used.

In one embodiment, after a step of insertion of a jellyroll 300 withinthe housing 100, the collectors at one end of the jelly-roll areelectrically coupled to the housing by welding. During welding, it isdesirable to press down onto the jelly-roll 300 so as to have a moreextensive contact and interface between the collectors and the housing100. In a preferred embodiment, welding is effectuated in a laserwelding step, wherein a beam of laser light 300 m (FIG. 5 f) is appliedin a particular pattern to the exterior bottom end of the housing 100.Preferably, the beam of laser light is of sufficient intensity to heatthe housing 100 and the collectors of the jelly-roll 300 so as tophysically and electrically bond the collectors to the housing 100without damaging the housing or the jelly-roll.

It has been identified that any impurities, dirt, residue, and/or overspray present at the inner bottom end 100 f can act to interfere withthe welding process. For example, it is identified that overspray fromthe application of the insulator 100 e to the interior walls of thehousing 100 can occur and be deposited on inner bottom end 100 f of thehousing. Such overspray can interact with the externally applied laserbeam by acting to locally increase the temperature at the point ofapplication of the laser light 300 m. Such increased temperature can actto burn through the bottom end of the housing 100 and/or damage thehousing and/or jellyroll 300.

Additionally, such increased temperature can act to interact with theinsulator 100 e to release or create impurities that can subsequentlyaffect operation of the jelly-roll 300.

After insulator 100 e is applied to the interior of the housing 100, theinsulator may be dried under appropriate temperature, and a jelly-roll100 is inserted within the housing (FIG. 5 f). Prior to insertion withinthe housing 100, the extending collectors of the jelly-roll 300 at bothends may be bent over such that coextensive surface contact between thecollectors can be achieved and such that better electrical and weldedcontact can subsequently be made thereto.

In one embodiment, wherein an extending collector associated with anoutermost electrode layer 300 a is coupled to the housing 100 (an“unflipped” jelly-roll orientation), and wherein direct electricalcontact between an outermost electrode layer and the housing 100 may bedesired to reduce electrical resistance between the housing and theoutermost collector of the outermost electrode layer, it is understoodthat the above described insulator 100 e would need to be applied onlyto the upper inner portion of the housing 100 that is used forsubsequent sealing.

To this end, it is identified that in an “unflipped” jelly-roll 300orientation, it may be preferred during or after manufacture ofcapacitor sheets 10 (FIG. 5H) to remove a portion of the electrode film40 and, if used, adhesive layer 50, from the sheet 10 corresponding tothe outermost electrode layer 300 a.

In one embodiment, prior to insertion within the housing 100, the end ofthe jelly-roll 300 that would extend from the open end of the housing isattached to the bottom end 600 b of the conductive metal 600 (FIG. 5 d).In one embodiment, the bottom 600 b is attached to the jelly-roll 300 byapplication of laser beam during a time the bottom is maintained incentralized contact with the end of the jelly-roll. The laser beam ispreferably of a magnitude that during welding of the bottom end 600 b tothe jelly-roll 300, the jelly-roll does not become damaged, but ofsufficient magnitude that solid connection is made to the collectors ofthe jelly-roll.

Referring to FIG. 5J, in one embodiment, the jelly-roll 300, is sealedwithin the housing 100 by placing the cover 200 onto the housing, and byapplication of a force to the cover 200 and the upper portions 100 a-bof the housing (FIG. 5 e) to mechanically curl the cover and upperportion at the same time and in a manner that the sealant 200 epreviously applied to the cover creates a hermetic seal against releaseand influx of gases, liquids, impurities, etc. and, as well, such thatthe insulator 100 e and 200 d previously applied to the housing andcover acts to electrically insulate the cover from the housing.

It is identified that during the step of applying the cover 200 to thehousing 100, the metal 600 (FIG. 5 a) will become further folded at thepreviously bent portions, and that when the cover is fully sealedagainst the housing, a spring action of the bent metal may act to applya downward force onto the jelly-roll 300. This spring action may help tomake better contact between the jelly-roll 300 and the housing 100 in anembodiment wherein the bottom end of the jelly-roll is laser welded tothe bottom end of the housing after the housing is sealed by a cover200.

In one embodiment, after a housing 100 is sealed by a cover 200, theresulting capacitor product may be impregnated with electrolyte byintroduction of the electrolyte through a sealable fill port 800.

Referring to FIG. 5 i, and preceding Figures as needed, in oneembodiment, a fill 800 is sealed by a separately applied metal, forexample, aluminum. In one embodiment, the applied metal is in the formof a disk 750. After introduction of electrolyte via fill hole 800within a housing 100 that has been sealed by a cover 200, anappropriately dimensioned disk 700 is placed over the fill hole, and anultrasonic welding process is used to attach the disk to the housing andto seal the fill port at the direct to metal contact exposed to theultrasonic weld.

In one embodiment, it is identified that by appropriate selection of athickness of the separately applied metal, the disk 750 itself can actas a “fuse,” which could be used in place or in combination withlongitudinal indentation 100 c (FIG. 5 e), in which case at somepressure, the disk 750 may be used to release electrolyte within asealed capacitor to render the capacitor safe and non-functional.

It is identified that the void within the jelly-roll 300 can be usedfacilitate the flow and impregnation of electrolyte within a sealedcapacitor. Because many of the collectors of the jelly-roll 300 haveduring an insertion step been folded over inward toward the center ofthe jelly-roll, thus potentially blocking flow of electrolyte from oneportion of the jelly-roll to another portion, the void in the jelly-rollcan be used to assist in circulating flow of the electrolyte. However,it has been identified when the metal 600 spring is attached to thejelly-roll 300, the bottom end 600 b of the metal spring may block theflow of electrolyte through the void within the jelly-roll. It isidentified that when a corresponding void 600 d or hole (FIG. 5 d) isprovided in the metal 600 spring, when such void 600 d is aligned to thevoid in the jelly-roll 300, it may subsequently facilitate flow ofelectrolyte within the sealed capacitor product.

In one embodiment, it has been identified that external permanentelectrical contact may sometimes be desired to be made to a battery formfactor sized capacitor product. As has been described throughout, in oneembodiment, a cover 200 and a housing 100 comprise aluminum. In oneembodiment, it has been identified that aluminum oxidizes easily and asa consequence aluminum is a difficult metal to make electricalconnections to. Without a provision for permanent electrical contacts,it is identified that contact resistance to ends of a double-layercapacitor product made of aluminum would be high, and at the highcurrents that double-layer capacitors may be used, excessive heat wouldbe generated. Permanent electrical contacts to a capacitor product canbe made by welding, but such welding entails high cost, both in moneyand time. In one embodiment, therefore, a housing 100 and/or cover 200may be provided with a thin cladding of metal. In one embodiment, themetal is an Nickel based cladding that can be provided by BI-Lame. Byproviding a cover an external layer of such, cladding, it has beenidentified that subsequent electrical contact to the cover can be easilymade, for example, by low heat soldering.

The above-described embodiment have been described. In doing so, anumber of benefits as well as disadvantages may have been noted by thereader. For example, the use of laser welding may cause damage to acapacitor cell, housing, or other component. The use of sealants andinsulators requires process steps that may be costly in both time andmoney. Sealing of a cover to a housing by curling may impact time andmoney, and as well affect reliability. Hence the present inventorssuggest in the following summary various changes, that alone, or incombination with features described herein can make a capacitor productmore reliable, cheaper, and more easy to manufacture.

Referring to FIG. 5 k, in one embodiment, a capacitor comprises ahousing 900 and a cover 902. In this embodiment no insulator andsealants are necessarily required. As well no necking and flanging isnecessary required. Such effect is achieved because a seal between thecover 900 and housing 902 can be achieved without the use of insulatorsand sealants discussed previously above. In one embodiment, the covercomprises a first disk 904, which may fittably inserted within anopening in a housing. Subsequent joining of the disk to the housing maybe performed by use of a conductive epoxy of the like, or by a weldingprocess, for example, laser welding. Prior to joining of the disk to thehousing, a jelly roll may be prepared in a manner similar to thatdiscussed above. At one end of the jellyroll 906 a bendable metal 908may be attached by welding to the jelly roll 906, the metal beingsubsequently attached and/or welded to the cover 902 or a portionthereof. Subsequently, prior to the insertion within a housing, bendablemetal foils or bendable metal tabs that are attached at an end of thejellyroll may be bent over to overlap a central portion of the jellyrollsuch that after the end of the jellyroll is inserted within the housingto abut against an inner bottom end of the housing, a welding tip may beinserted within the central void formed within the jellyroll to abutagainst the bent foils and/or tables. The bend foils and/or tabs cansubsequently be welded to the interior end of the housing. Such weldingthrough the void in the jellyroll eliminates a blind weld that wasdescribed in the previously described laser weld process to occur fromoutside of the housing. By eliminating the blind weld, defective weldsare more easily able to be identified. As well, as a consequence,because jointment between the jellyroll collectors foils can be morereliably made at to bottom end of the housing, the ESR of the capacitormay be improved. When welding through the central void of a jellyroll,it is identified that the previously described fill hole may need to bepositioned at some other location.

In one embodiment, the cover is comprised of a number of components,that when assembled, provide a seal against leakage of subsequentlyintroduced electrolyte. As described above, a cover comprises a firstdisk 904 (washer negative). In one embodiment, the first disk has acentrally disposed void within which a slightly smaller metal piececomprising a protrusion can be placed (lid positive 910). At one end ofthe metal piece, the bendable metal 908 used to connect to the upper endof the jelly roll collectors can subsequently be attached to frame aspring. The first disk and metal piece are dimensioned such that when asealing separator (seal EPDM 912) is placed over the protrusion, andwhen the protrusion is inserted within the void of the first disk, theprotrusion extends through the void in a manner that a seal may beformed therebetween. At a side of the first disk through which theprotrusion extends, over the protrusion is placed a insulating separator(insulation washer 914) that electrically insulates and separates theprotrusion, and hence the metal piece form the first disk, and as well asubsequently place retaining right (retaining washer 916). The retainingring is as well shaped as a second disk with a centrally disposed voidthat has dimension that allow the void of the second disk to forciblysnapped over the protrusion such that the rubber separator and theplastic separator can be maintained in sealable contact with the firstdisk. The resulting cover structure comprises a central portion (metalpiece with protrusion snapably coupled to second disk) that is sealablyand electrically isolated from the first disk. Subsequent bipolarelectrical contact to a jellyroll capacitor cell can be thus madeseparately through the second disk, and separately to the retaining ringor the housing that the first disk is electrically coupled to (FIG. 5L)

It is identified that because the capacitor housing need not, thus, benecked or flanged radial electrical attachment to the capacitor can moreeasily be facilitated. In one embodiment an electrical connect or tabcan be electrically attached or be part of one end of the housing, andanother electrical tab can be attached or be made part of the seconddisk. Such tabs can extend in the same direction to facilitateattachment to RCBs in a vertical configuration (FIG. 5M).

It has been identified by the inventors that electrical interconnectionsbetween capacitors connected in series or parallel can be made usingthermally fitted bus bars or interconnects where voids of aninterconnect can be thermally expanded to fit over correspondingterminals. With similar materials (for example, aluminum) used for theterminals and interconnects, subsequent cooling of the interconnectscauses the voids to contract about corresponding terminals to form agood mechanical/electrical connection. Capacitors or other devices canin this manner interconnected (mechanically and/or electrically) withoutthe use of additional materials, such as screws, clamps, solder, welds,etc.

In one embodiment, it has been identified that housing and/or covers maybe themselves be used to provide similar interconnect functionality. Forexample, in one embodiment, a cover of one capacitor is shaped withprotrusion, and a housing of another capacitor is shaped with recessthat can accommodate the protrusion. In one embodiment, the recess isdimensioned to have the same or slightly smaller dimension than theprotrusion (FIG. 5N). For example, in one embodiment, the protrusioncomprises a cylindrical shape, and the recess defines a cylindricalshape, wherein heat applied to the housing may be used to expand thediameter of the recess, which may then be placed over the terminal.Subsequent equilibration of the temperature for the recess and theterminal allows that a reliable mechanical and electricalinterconnection can be made without the use of a bus bar. Suchinterconnection can be maintained over a wide range of temperatures toconnect devices such as capacitors together.

In one embodiment, wherein initially a cover and/or a housing does notcomprise an adequately dimensioned protrusion or void, the cover and/orhousing may be modified. For example, a protrusion may be coupled to acover or a housing, and/or a component with a recess can be coupled tothe housing or the cover. In one embodiment, the coupled protrusion andthe component with a recess may respectfully comprise a disk and awasher like element, wherein the disk fits within a void within thewasher. In one embodiment, the protrusion and element with a void may becoupled to a respective cover and housing by means of welding,conductive glues, and others known to those skilled in the art.

Although the particular embodiment described herein are fully capable ofattaining the above described advantages and objects of the presentinvention, it is understood that the description and drawings presentedherein represent some, but not all, embodiments of the invention and aretherefore broadly representative of the subject matter which iscontemplated by the present invention. For example, a double-layercapacitor and/or housing may be designed to confirm to a standardizedC-cell battery form factor, an AA-cell battery form factor, or anAAA-cell battery form factor. The above identified principles andadvantages may be applied to standardized housing of other batterytechnologies, for example, NiMh, lithium, alkaline, Nicad, sealedlead-acid, and the like. The above identified principles and advantagesmay also be applied to other batteries and form factors that may exit orbe developed and accepted in the future as standardized. As well, theinsulation and sealants described herein may vary or be different inother embodiment. It is therefore understood that the scope of thepresent invention fully encompasses other embodiments that may becomeobvious to those skilled in the art and that the scope of the presentinvention should accordingly not be limited.

1. An energy storage device, comprising: (a) a jelly roll, comprising:(i) a first sheet, having a top side and a bottom side, comprising: (A)at least two electrode films, operatively coupled to a first currentcollector plate, wherein a first electrode film is disposed along thetop side of the first sheet, wherein the second electrode film isdisposed along the bottom side of the first sheet; (ii) a second sheet,having a first side and a second side, comprising: (A) at least twoelectrode films, operatively coupled to a second current collectorplate, wherein a first electrode film is disposed along the first sideof the second sheet, wherein a second electrode film is disposed alongthe second side of the second sheet. (iii) a first separator member,having an upper side and a lower side, wherein the separator memberupper side is operatively coupled to the first sheet second electrodefilm, which is disposed along the bottom side of the first sheet,wherein the separator member lower side is operatively coupled to thesecond sheet second electrode film, which is disposed along the secondside of the second sheet; (iv) a second separator member, having aninner side and an outer side, wherein the inner side of the secondseparator member is disposed along and operatively coupled to the firstsheet first electrode film, which is disposed along the top side of thefirst sheet, and; (b) at least one terminal element, having a proximateend and a distal end, wherein the proximate end is in electrical contactwith the jelly roll and the-distal end protrudes therefrom the jellyroll.
 2. The energy storage device of claim 1, wherein the jelly roll isadapted store at least 250 Farads.
 3. The energy storage device of claim2, further comprising a battery form factor housing.
 4. The energystorage device of claim 3, wherein the housing comprises the aluminum.5. The energy storage device of claim 4, wherein the battery form factorhousing comprises: (a) a diameter of approximately 33±1 millimeter, and;(b) a height of approximately 61.5±2 millimeters.
 6. The energy storagedevice of claim 4, wherein the battery form factor housing comprises:(a) a diameter of approximately 25.2±1 millimeter, and; (b) a height ofapproximately 59.5 to 1.5 millimeters.
 7. An article of manufacture,comprising: (a) forming a cylindrical housing having an exterior surfaceand an interior surface, and; (b) stamping a longitudinal indentionoriented along a longitudinal axis, wherein the longitudinal indentationis stamped on the exterior surface of the cylindrical housing.
 8. Thearticle of manufacture of claim 7, wherein the longitudinal indentationis adapted to weaken the cylindrical housing under an exerted pressure,wherein the longitudinal indentation is further adapted to slowlyfracture under a pressure exerted therein the cylindrical housinginterior surface.
 9. The article of manufacture of claim 8, wherein thecylindrical housing is further adapted to prevent a catastrophicexplosion of the exterior surface of the cylindrical housing, wherebythe longitudinal indentation is adapted to safely render the article ofmanufacture non-functional via slow fracture of the longitudinalindentation.
 10. A means for storing electrical energy within a housingmeans, comprising: (a) a jelly roll means, disposed inside the housingmeans, for storing electrical energy, and; (b) a terminal means,responsive to the jelly roll means, for transferring electrical energybetween the jelly roll means and an external contact.